The present invention relates to a front substrate for AC plasma display panel, and more particularly to such a front substrate in which each X-electrode and Y-electrode have a respective discharge side facing to each other and arranged in parallel, defining therebetween a straight discharge path. The invention relates also to the fabrication of such a front substrate.
In the fabrication of a conventional AC plasma display panel 10, as shown in FIG. 1, a front substrate 11 and a rear substrate 12 are arranged in parallel and encapsulated, and a gas mixture containing Ne and Xe is sealed in the discharging space between the substrates. The front substrate 11 comprises parallel transparent electrodes 111 arranged on its inner side, parallel sub electrodes 112 respectively arranged on the transparent electrodes 111, an induction layer 113 covered over the electrodes 111 and 112, and a protective layer 114 covered on the induction layer 113. The rear substrate 12 comprises a plurality of data electrodes 121 arranged in parallel on its inner side, an induction layer 124 covered over the data electrodes 121, parallel lines of partition wall 122 arranged on the induction layer 124 and extended to the protective layer 114 at the front substrate 11, and fluorescent body 123 covered on the induction layer 124 around the lines of partition wall 122. When electric voltage is applied to the electrodes 111, 112 and 121, electricity is discharged in the cells 13 between the induction layers 113 and 124, causing the fluorescent body 123 to emit the corresponding color of light. In the fabrication of the front substrate 11 of the aforesaid AC plasma display panel 10, a photolithography or printing technique is used to make transparent electrodes 111 on the inner side of the front substrate 11, and steam-plating and photolithography techniques are used to form sub electrodes 112 on the transparent electrodes 111 to reduce the line impedance of the transparent electrodes 11. In the following description, X-electrode and Y-electrode are used to represent each two adjacent transparent electrodes 111 (including the corresponding sub electrodes 112) on the front substrate 11. The two electrodes act with one data electrode 121 at the rear substrate 12, enabling the induction layers 113 and 124 to discharge electricity into the corresponding cell 13. In the aforesaid front substrate 11, the equivalent circuits formed upon discharging of the X-electrodes and Y-electrodes are as shown in FIG. 2, in which Cg is gas-filled capacitor, Cd is induction layer capacity, Cs1 and Cs2 are stray capacity produced in the glass substrate 11 and the induction layer 113. The equivalent circuits can be simplified into a parallel circuit formed of capacities Cg and Cd and capacities Cs1 and Cs2 and connected between the X-electrode and Y-electrode as shown in FIG. 3. In the aforesaid X and Y electrodes design, the discharging sides of the electrodes are almost arranged on the same level, and the discharging paths are presented in an arch shape. This design has the following drawbacks.
1. Uneven distribution of electric field: As shown in FIG. 4, the intensity of the electric field becomes stronger at the center area between the X-electrode and the Y-electrode, causing a relatively better discharging effect and a stronger intensity of UV light to be produced at the center area between the X-electrode and the Y-electrode.
2. Complicated equivalent circuits being not easy to be driven: As illustrated in FIG. 5, different equivalent circuits are produced subject to different discharging paths, and the equivalent circuits formed of the gas-filled capacity Cg and the induction layer capacity Cd cannot be simplified after driving of the electrodes.
3. Limited operation range of driving voltage: Because different discharging paths have different V-I curves, as shown in FIG. 6, memory margin is relatively limited to the plasma display panel.
4. False discharge due to uneven accumulation of electric discharges: Because the intensity of electric field is relatively stronger at the center area between the X-electrode and the Y-electrode, space charge tends to be gathered at the electrodes near the center area, as shown in FIG. 7, inviting a false discharge.
The present invention has been accomplished to provide a front substrate for AC plasma display panel, which eliminates the aforesaid problems. It is one object of the present invention to provide a front substrate for AC plasma display panel, which enables the discharging sides of each X-electrode and Y-electrode to be disposed in parallel for producing a uniform electric field and electric plasma to prevent striking of ions against the fluorescent layer on the rear substrate of the plasma display panel, so as to improve the surface life of the plasma display panel. It is another object of the present invention to provide a front substrate for AC plasma display panel, which keeps the discharge paths in the electrodes to be maintained in straight, so as to greatly improve the intensity of the electric field and UV light, and to effectively reduce the driving voltage value. It is still another object of the present invention to provide a front substrate for AC plasma display panel, which enables same equivalent circuits to be produced corresponding to the discharge paths when the electrodes are driven. It is still another object of the present invention to provide a front substrate for AC plasma display panel, which enables electric charges to be evenly accumulated at the electrodes to fix the range of memory effect, so as to prevent a false discharge due to a potential turbulence.